As disclosed in Patent Literature 1, a molding (weather strip) is installed on upper ends of an outer panel and an inner trim configuring a door panel of an automobile; a lip section of the molding is brought into contact onto a window glass surface so that droplets and dusts will not enter the door panel in its inside at an occasion when the window glass is lowered.
As for the above described molding installation, automatic installation with a robot is carried out conventionally. That automatic installation is carried out by position control with a robot subjected to teaching of an installation position.    Patent Literature 1: Japanese Patent Application Publication No. 10-100681
As described above, conventionally a molding is installed by automatic installing with a robot. However, installation is carried out only by controlling the positions of the robot. Therefore, unreasonable force is applied to the molding and the automobile body which can be occasionally damaged. In order to avoid this, a dedicated device for detecting abnormal operations is required beside the installation robot, giving rise to cost increase and deterioration in workability.